1. Field of the Invention
The present invention relates to a vacuum arc vapor deposition apparatus, which can be used for depositing thin films on objects or works such as automobile parts, machine parts, tools or dies for the purpose of improving at least one of wear resistance, sliding property, corrosion resistance and others.
2. Description of Related Art
According to a vacuum arc vapor deposition apparatus, vacuum arc discharge is caused between an anode and a cathode to vaporize a cathode material by the arc discharge, and plasma containing the ionized cathode material is produced to disperse the ionized cathode material onto a deposition target object or work so that a thin film is deposited on the deposition target object.
For generating the arc discharge between the anode and the cathode, a trigger electrode for inducing the arc discharge is opposed to a discharge surface of the cathode, and a voltage is applied across the cathode and the trigger electrode. Further, the trigger electrode is brought into contact with the discharge surface, and subsequently is spaced therefrom to cause the arc discharge so that the arc discharge is induced between the anode and the cathode.
The cathode and the trigger electrode, which is opposed to the cathode for inducing the arc discharge, are generally and collectively referred to as a vapor source.
According to such a vapor source, vacuum arc discharge is often interrupted during film deposition if the cathode is made of certain kinds of material (particularly, if the cathode is primarily made of carbon). Whenever the arc discharge is interrupted, the vacuum arc discharge is induced between the anode and the cathode by using the trigger electrode, which is provided for inducing the arc discharge, so that the film deposition is resumed.
However, the arc discharge is unstable when the vacuum arc discharge is induced between the anode and the cathode by the trigger electrode (this induction may be referred to as “arc ignition” hereinafter). Therefore, when the arc ignition is repeated for the film deposition, this lowers the film quality.
In the case where a cathode primarily made of, e.g., carbon is used for film deposition, the vacuum arc discharge is repetitively interrupted during the film deposition, and the arc ignition is performed every time such interruption occurs. Therefore, the deposited film has a large surface roughness.
In connection with this, Japanese Laid-Open Patent Publication No. 2002-25794 has proposed that a shield member is interposed between a vapor source and a deposition target object for shielding them from each other when arc ignition is performed.
However, it is necessary to deposit a film of good quality without uselessly increasing the time from start of deposition of a film having a predetermined thickness to completion of such film deposition. For satisfying the above, a shield member must be moved to and retracted from a position between the vapor source and the deposition target object in accordance with appropriate timing corresponding to interruption or turn-off of the vacuum arc discharge and the arc ignition. However, such moving and retracting operations are actually difficult.